Reversing-furnace mechanism



May 20 1924.

5 Sheets-Sheet 3 J5 is my l n M C STEESE REVERSING FURNACE MECHANISM Flled July 15 1920 'May zo, 1924. 1,495,119

M. C. STEESE 'REVERBSING URNACE MECHANISM Filed July l5, 1920 5 Sheets-.Sheei'f` Patented May 20, 1924.

MARCUS C. STEESE, OF HAMBURG, NEV YORK. y

IREVEIR-SNG-FURNACE MECHANISM.

Application lcd July 15, 1920. Serial No. 396,437.

To all 'whom t may concern:

Be it known that I, MARCUS C. S'rnnsn, a

citizen of the United States, residing at Hamburg, in the county of Erie and State of New York, have invented certain new and useful Improvements in Reversing-Furnace Mechanism, of which the following is a specification.

This invention relates to reversible furnace mechanism, and finds particular application in open hearth furnaces, and, as a matter of fact, in any heating'furnace of the reversing regenerative type.

In the operation of reversible regenerative heating furnaces, as, for example, the open hearth furnace, gas and air are fed through their respective chambers to the ports of the furnace, where the gas and air mix, resulting in combustion for producing the necessary furnace heat, the products of` combustion being passed out through the air and gas chambers at the opposite end of the furnace and to the stack. Preparatory to reversing the furnace, the gas supply is shut off at the first end of the furnace. However, under such conditions the gas passageways and gas chamber'connecting the main gas supply inlet and the gas ports of the furnace still contain a large quantity of gas. Unless such remaining gas is properly used or disposed of before the furnace is reversed, violent explosions are apt to occur, resulting in great damage to or destruction of the briclrwork and fines.

Accordingly, one object of this invention is to prevent explosions in reversible furnaces and the disastrous results occasioned thereby.

Another object is to purge the entire system of a. reversible regenerative furnace of any explosive medium, such as gas, in a simple. novel and efficient manner prior to a reversal of the furnace, the purging action taking place at the proper time and delinitely related and controlled by the operation of associated parts.

Another object is to prevent the waste of conduis-tilde gas when reversing the furnace and thereby increase the efficiency of the furnace.

These and other objects are accomplished by means of the arrangement disclosed on the accompanying sheets of drawings, in

which- Figures 1 to 8, inclusive, show somewhat' diagrammatically and schematically, an arrangement of valves for a reversible' open hearth furnace, and means for controlling same to accomplish the desired results, the valves in the various figures being shown in different positions to effect the proper operation of the furnace in reversing the same. The significance of the positions of the various valves and controlled parts inthe different figures'of the drawings will -be par-` ticularly referred to throughout the *specification; y

Figure 9 is a fragmentary detail plan view of an operative connection between a gas reversing valve and a gas shut-off valve at one end of the furnace, said connection including a purge valve interconnected with and the operation of which is controlled by said associated gas reversi-ng and gas shut-off valves;

Figure-10 is a fragmentary front elevation of the same arrangement;

Figures 11 and 12 are views taken along the lines 11-11 and 12-12, respectively, of Figure v10; and, i

Figure 15 isl a view similar to those shown in Figures 1 to 8 inclusive and in addition showing connections from a stack whereby products of combustion may be supplied and controlled by the purge ,valves for purging purposes.

In Figures 1 to 8, inclusive, and '13, an.

open hearth furnace 10 is shown having the two voperative ends No. 1 and No. 2,. No. 1 end of the furnace is provided with an air chamber 11 and `gas chamber. 12, and No. 2-

end of the furnacesimilarly Iis provided withv an air chamber 13' and gas chamber 14. Air is supplied to the air chamber.v v11 through an air lid 15 and through a connecting passageway 16 when the air reversing valve 17 is removed from the air valve seat 18. The gas is supplied' to the gas chamber 12 through passageway 21 from a gas supply main 19 when the gas shut-off valve 2O is in open position, the gas reversing valve its associated gas shut-off valve is open. As

shown in Figures 1, 2 and 6, the air re- 22 being in closed position wheny versing valve 17 and gas reversing valve 22 cover the stack connections 23 and 24, respectively. In connection with No. 2 end of the furnace, air is supplied through an air lid 25 and passageway 26 when the air reversing valve 27 is removed fromv its valve seat 28. Gas is supplied to the gas chamber 14 from a gas supply main 29 through a gas passageway 30 when the gas shut-off valve 31 is open and the associated gas reversing valve 32 is closed., The gas reversing valve 32 controls the flow of products of combustion passing outwardly from the gas chamber 14 to the stack connection 33, and the air reversing valve 27 also controls the passage of products of combustion passing outwardly from the air chamber 13 to the stack connection 34 when gas is supplied from the opposite end of the furnace. The gas shut-off valves 2O and 31 are controlled by levers 35 and 36, respectively, pivotally supported at points 37 and 38, respectively, the limits of movement of said levers 35 and 36 being controlled by stop members 38 and 39 for lever 35 and stop members 40 and 41 for lever 36. A single lever 42 is provided for controlling and operating the air reversing valves 17 and 27, said lever being connected to said valves, respectively, by flexible members 43 and 44, which pass over sheaves 45 and 46, respectively. A single lever 47 operates and controls the gas reversing valves 22 and 32, respectively, said lever being connected to the valves 22 and 32, respectively, by flexible members 48 and 49, respectively, which pass over sheaves 50 and 51, respectively.

Thus far in connection with the valve mechanism attention has been called only to the air reversing valves, gas reversing valves and gas shut-off valves. In addition to these valves, I have provided a purge valveat each end of the furnace whereby the entire system of the furnace may be purged of all combustible gas coming from either gas main 19 at one end or gas main 29 at the other end of the furnace prior to reversing the furnace. Not only is it of great value to provide purge valves for accomplishing the above-mentioned result, but also it is of prime importance that the purging action should take place at a definite relativetime and just prior to the reversal of the supply of air and gas to the furnace. To properly time and cordinate the purging action with the shut-off of the gas and reversing of the furnace, I have provided, an interlocking connection between the gas reversing valve and the gas shut-off valve at each end of the furnace, said interlocking connection in each case including a purge valve, each of which under certain conditions is actuated in accordance with separate movements of the associated gas reversing valve `and gas shut-off valve; for

instance, the purge valve 52 at No. 1 end of the furnace, under given conditions, is responsive to movements of the associated gas reversing valve 22 and the gas shut-offz valve 20. Likewise the purge valve 53 at No. 2 end of the furnace, under given conditions, is responsive to movements of the associated gas reversing valve 32 and the gas shut-off' valve 31. The connection between the gas reversing valve and gas shutoff valve, including` the associated purge valve, comprises a plurality of associated levers shown in detail in Figures 9 to 12, inclusive. The lever arrangement shown` in said figures is the one applied to No. 2 end of the furnace,y but it will be understood that the lever arrangement at No. 1 end of the furnace acts in the same manner. same reference characters which are applied to the interlock between gas shut-off valve 31 and gas reversing valve 32at No. 2 end of the furnace will be used but primed in connection with the corresponding interlock at No. 1 end of the furnace.

In the arrangement shown in Figures 9 to 12, inclusive, there are two levers 54 and 55, an intermediate portion of the former being connected to one end of the latter by a link 56. Lever 55 is pivotally connected at 57 to any suitable support, and lever 54 in effect is a floating lever suspended from lever 55 by the link 56. I-Iung from one end of the lever 54 is the purge valve 53, the stem of the latter being guided between suitable guides 58. The opposite end of the lever 54 isoperated between a stop member 59 at the lower side of the lever and a projection 60 at the upper side of the lever and carried on the stem of gas shut-olf valve 31. The upper side of the free end of lever` 55 is operated upon by a projection 61 carried by the stem of gas reversing valve 32. As shown in Figure 1 of the drawings, gas shut-off valve 31 is closed, gas reversing valve 32 is open, and purge valve 53 is closed, the free end of lever 54 resting upon its stop 59. In Figure 4 it will be noted that the gas reversing valve 32 has been lowered, its projection 61 passing into engagement with the free end of lever 55 and causing the purge valve 53 to be opened through the action of levers 55 and 54, the latter fulcruming above its stop .member 59. With the parts in the position shown in Figure 4, the gas shut-olf valve 31 may be raised into the position shown in Figure 5. During the first part of the opening movement of the gas shut-off valve 31 the purge valve 53 closes as a result of its own weight, the lever 54 pivoting about its point of pivotal connection 62 with the link 56, the free end of the lever 54 rising' from stop member 59 The under the influence of the weight of the l shown in Figure 5, the gas shutoff valve 31 may be closed, whereupon the purge valve 53 will be opened because of the projection 60 of the gas shut-olf valve 31 passing into engagement with the upper side of lever 54k for lifting the purge valve 53 into an open position, as shown in Figure 4;. lVith the parts in such position an opening of the gas reversing valve 32 will permit the purge valve 53 to move into closed position, as shown in Figure 1, the Weight of the released purge valve causing the closing movement, the weight of the purge valve acting through lever 54: then fulcr'umed against its stop member 59, through link 56 and lever 55, the free end of lth-elatter rising with the projection 61 on gas reversing valve 32 until the purge valve 53 is seated, further opening movement of the gas reversing valve 32 being unaccompanied by any movement of the purge valve. Such is the action and control of the purge valve by the gas shut-off valve and the gas reversing valve. With this understanding, the `operation of the whole system will be considered.

Assume, first, that the parts are in the position shown in Figure 1. Under such conditions it will be noted that the air reversing valve 17 and the gas reversing valve 22 at No. 1 end of the furnace are closed, ready to receive gas from the gas main 19, the gas shut-olf valve 2O at this time, however, being closed. Purge valve 52 at this time is held in open position by the gas reversing valve 22. Upon raising or opening the gas shut-off valve 20 for admitting the supply of gas over the gas reversing valve 22, the first few inches of motion permit the closing of purge valve 52, whereupon any further opening movement of the gas' shut-olf valve 2O at No. 1 end has no effect upon the purge valve 52. rllhe last part of the movement of gas shut-olf valve 20, which does not affect the purge, is utilized in regulating the volume of iiow of gas. The opened gas shuteoff valve 20, with the closed purge valve 52, is shown in Figure 2 of thedrawings. Gas being supplied from the gas main 19 flows past the closed purge valve over the gas reversing valve 22 and in through gas chamber 12 to the gas port in the furnace, not shown, where it meets air which comes in from air lids 15 over the air reversing valve 17 at No. 1 end of the furnace through the air chamber 11 and to the air ports of the furnace, not shown, there meeting and Vmixing with the gas. Combustion takes place in the furnace and the products of combustion pass outwardly from the furnace through the gas and air ports on the other or outgoing end. These waste gases which ,have passed out through the air port, pass through the air chamber 13 and to the air reversing valve 27, which is raised,

sealing olf the connection to the atmosphere through the air lids 25, saidl waste gases, therefore, passing underneath the air reversing valve 27 to the stack connection 34. The waste gases which pass out through the gas port at No. 2 end of the furnace pass through the gas chamber 14 and out below the gas reversing valve 32 to the stack con-v nection The gas shutolf valve 31- at No. 2 end of the furnace being closed and its associated purge valve 53 being closed, there is no flow of gases from either of said sources to the stack.

ln reversing the open hearth furnace with a purge valve in accordance with my invention, all operations are the same as the operations upon a similar system without a purge valve. First the gas shut-off valve 20 on No. 1 end is closed, the first part of its motionl not affecting the position Of'its associated purge 'valve 52. rlhe last few inches of the down stroke of the gas shut-v off valve 20, however, raises thepurge valv-e 52, as shown in Figure 1 of the drawings.

The gas being shut ofi', the purge valve '1sl automatically opened t0 the atinosphereor to a supplv of waste gases. ALt this point it may be stated that the temperature in the gas chamber and air chamber, and the gas uptakes and airuptakes, on all sides create a slight suction upon the and air reversing valves. This suction draws in through the purge valve 52 air or products of combustion on No.1 side, which displaces the gas in the gas valve chamber and passageway 21, gas chamber 12, and in the gas uptakes leading to the intake ports of the' furnace. vThis 'gas burns as it did when the supply of gas was furnished tl'iroughthe shut-off valve 20 on No. 1 end. Then the flame in the port on No. 1 end ceases, all the in the gas chamber on No. 1 end has been displaced by air or waste gases and the furnace then is readv for reversal with no danger of explosion, there being no unburned gases in the system. rlhe air reversing valves 17 and 27 and reversing valves 22 and 32 are then thrown over through an intermediate position shown in Figure 3 b v an operation of their levers -CVK' and 42. The first few inches of motionin throwing over the reversingv valves closes the purge valve at No. 1 end of the furnace. lt will be noted that the purge valve 52 is closed before the gas reversing valve 22 opens the connection `between the `gas chamber 12 andthe stack connection 211 on No. 1 end. The purgev valve 53 on No.

2 end still is closed and will not open 'until the gas reversing valve 32 on No. 2 end has entered the seal and cut off the connection from the gas chamber 1e to the stack conllO nection 33 on that end.' Continuing the reversing movement from the position shown in Figure 3, the last few inches of the downward movement of the gas reversing valve 32 opens purge valve on No. 2 end, this arrangement being` shown in Figure 4 of the drawings. r1`he opening` of the purge valve 53 at this instant serves no purging function, but permits of inspection of the associated gas shut-off valve 31 to determine whether gas is'leaking from the gas main 29. The furnace being ready to receive from No. 2 end` the operator raises the gas shut-off valve 31, as shown in Figure The first few inches of the opening movement of the gas shut-off valve 31 permits the purge valve to close. The remaining opening movement of the gas shut-off valve 31 is unaccompanied by any movement of the purge valve, said further opening movement of the gas `shut-off valve serving as means for regulating thefquantity of flow of gas to the furnace. Gas from the No. 2 end supplied from the gas main 29 flows past the closed purge valve 53, over the gas reversing valve 32 to gas chamber 14, and then through the flues and uptakes to the portof ther open hearth furnace, the stack connection 0n No. 2 end being cut off by the gas reversing valve Air is admitted from the atmosphere through the air lids 25 on No. 2 end through the air chamber 13, corresponding fines and uptakes to the air port of the furnace, where the air and gas combine and combustion tak-es place. The waste gases pass outwardly from the furnace through the outgoing air and ports on No. 1 end, down through the uptakes. through air chambers and chambers to the stack connections 23 and 24. under the air and reversing valves 17 and 22, respectively, it being noted that the connection to the atmosphere on No. 1 end through the air Alids 15 is sealed off by the upper position of the air reversing valve 17. rlhe gas main 19 on No. 1 end being closed and the purge valve 52 being automatically closed, there is no connection between the stack and the gas main or between the stack and the atmosphere, or any other source of purge fluid to the stack through the gas reversing valve 22 on No. 1 end.

iVhen ready to reverse the furnace from lilo. 2 end to No. 1 end, the operator first closes the gas shut-off valve 31 on No. 2 end of the furnace, the first part of the closing` movement of the gas shut-off valve 31 not affecting the position of the associated purge valve 53, the last few inches of the closing movement of the gas shut-off valve 31, however, raising or opening the associated purge valve 53, as shown in Figure L1 of the drawing, whereupon the suction due to the hot gas chambers and the uptakes draws in through the purge valve on No. 2 end of the furnace, air or products of combustion displacing the combustible gas in the gas chamber, flues and uptakes. `When the. flame dies out in the ports on No. 2 end, the operator then reverses his gas reversing and air reversing valves through their levers a7 and 42, the first few inches of opening movement of the gas reversing valve 32 on No. 2 7

end of the furnace permitting the associated purge valve 53 to close, as shown in Figure 3 of the drawings, the purge valve being closed before the associated gas reversing valve 32 is drawn from the seal of the stack connection As the reversing mo-V tion continues after the gas reversing` valve 22 on No. 1 end has proceeded in itsdownward closing motion far enough to enter its seal. a further closing motion'thereofraises its associated purge valve 52, as shown in Figure 1 of the drawings. Again it may be mentioned that at this instant the opening of the purge valve serves no function other than that it gives an opportunity at this time to ascertain whether or not there is any leak of gas from the gas main 19 past its shut-off valve 2O on No. 1 end of the furnace. Now the furnace is ready to receive gas on No. 1 end and immediately the operator opens gas shut-off valve 20, its first few inches of upward movement permitting its associated purge valve 52 to close and any further movement of the'gas shut-off valve 2O being` to regulate thek quant-ity of flow of the gas on No. 1 end of the furnace. This arrangement is shown in Figure 2 of the drawings. A complete cycle in the regular operation of the furnace has now been considered. y

Attention will now be called to some irregular operations which are the result of mistakes, but it vill be'shown that in no case will the purge valve and its operative relation to its associated gas reversing valve and gas shut-off valve adversely affect the operation or condition of the furnace.

In this connection attention is directed first to Figure 6 of the drawings, wherein it will be noted that the operator has made the mistake of opening the gas shut-offl valve 31 on No. 2 end of the furnace when gas also is being supplied in a regular inanner on No, 1 end of the furnace. /Vith gas shut-off valve 31 open under the conditions imposed, a connection is made between the gas main 29 and the stack connection 33 under the gas` reversing valve 32. This condition sometimes exists in the practice 'ofreversal where no purge valve is used, and the purpose of illustrating this mistake in the operation is to show that it is made no worse where the purge valve is used, it being noted under the conditions imposed that the purge valve 53 remains closed, or, in other words, unaffected by the opening of the gas shut-off valve 31. `Serious results are a factor in such mistake, but the mistake would 'be more'serious if the associated purge valve 58 were open at the same time for admitting air along with the gas, which would cause violent explosions. Accordingly, by inserting in the system a purge valve controlled in the manner that it is, no

evils 4are injected into the system.

Another abnormal condition exists in the arrangement shown in Figure 7 of the drawings. It will be noted that the operator has vfailed to close the gas shut-'off valve 20 beassociated purge valve 52 remains unaffected,

or, in other1 words, remains closed, and accordingly no air is passedin the purge valve opening to miX with the gas from the `gas main 19 for causing disastrous explosions. l The gas which issues from the gas main 19 under these conditions passes outwardly throughstack connection 24. It is seen, l

therefore, when the mistake above indicated is made, the purge valve does not inject a faulty point in the syst-em.

A third mistake which is sometimes made inthe operation of open hearth furnaces withoutl purge valves is indicated in Figure 8 of the drawings, wherein it will be noted that with the gas shut-off valve 2O still in an open position, the air vreversing valves 27 and 17 have been reversed by mistake. It will be noted, however, that Aa reversal of the air reversing valves in no wise affects the position of the purge valves, the same remaining closed. n

I wish to make it clear that the purge valve may control either a supply of air from the atmosphere or of other gases, such as products of combustion fed from any suitable source, such as a stack. In this connection see Figure 13, wherein a stack is shown from which products of combustion vare drawn, inopposition to the stack draft,

b v a low pressure fan 66 and forced through pipes 67 and 68 to'the ports controlled by thel purge valves 53 and 52 respectively, Suitable'regulating dampers 69 and 70 pref' erably are provided in the pipes 67 and 68 respectively. It will be understood that my invention is to be considered broadly enoug to include any suitable purgingmedium. l

By means of my invention explosions which cause damage to the briclrwork ,and

flues of reversing furnaces are overcome,

' and not only this, butall the gas fed to the open hearth and what remains in the gas chambers, flues and uptakes'at thetime of reversal is completely used in' the furnace for producing heat. In other words, no gas is wasted upon a reversal of the furnace,y thereby increasing the efficiency of the furnace. In ordinary practice the loss caused by the waste of gas upon reversal amounts to 5 per cent of the amount of fuel consumed. i f

It is my intention to cover all modifications of the invention` falling` within the spirit and scope of the followingY claims.

I claim:

1. In reversing furnace mechanism, the combination of a gas shut-off va1ve,-a purge valve for controlling the purging of the furnace of gas, and means for interlocking said valves wherebyunder certain conditions one is controlled by the other and whereby under certain other conditions one is not controlled by the other. I

2. In reversing furnace mechanism, the combination of a gas shut-ofi' valve, a purge valve for controlling the purging of the furnace of gas, and means whereby the purge valve will be controlled by the gas shut-off y 'valve under certain conditions and whereby `valve for controlling the purging of the furnace of gas, and means whereby under certain conditions said purge valve will. be opened 'by a closing movement of said gas shut-off valve and whereby under ycertain other conditions said purge valve will not be a'ected byl a' closing movement of said gas shut-off valve.

4. In reversing furnace mechanism, the combination of a gas shut-off valve, `a purge valve for controlling the purging of the furnace of gas, and means whereby under certain vconditions said ypurge valve will be opened during a closing movement of said -gas shut-off valve and whereby under certain other conditions the purgev will-not be operated by movement of said gas shut-off valve.

5. In reversing furnace mechanism, the combination of a gasshut-oif valve, a gas reversing valve, and an operative connection between said gas shut-offl valve and gas recombination of a gasshut-off valve, a gas n 'reversing valve, a purge valve whereby the furnace may be purgedl of gas, said `three valves'being interlocked so that under certain conditions a movement of a certain one of said valves will be dependent upon movement ofsaid other valves. n

7. In` `reversing furnace vmechanism, the combination of a gas shut-olf valve, a gas reversing valve, a purge valvewhereby the furnace( may be purged of gas, said three valves being interlocked so that under certain conditions a movement of the purge valve will be dependent upon the movement of said other valves. l

8. In reversing furnace mechanism, the combination of gas reversing valves at opposite ends of the furnace, a purge valve at each end of the furnace, and means whereby the purge valves will be given a reversing movement when said gas reversing valves are given a. reversing movement.

9. In reversing furnace mechanism, the combination of gas reversing valves at opposite ends of thefurnace, a purge valve at each. end of the furnace, and means whereby the purgev valve at one end of the furnace will be closed and the purge valve at the other end opened as the gas reversing valves are reversed. i

10. In reversing furnace mechanism, the combination of gas reversing valves for opposite ends of the furnace, a purge valve for each end of the furnace, and means whereby the purge valve for one end of theA furnace will be closed and the purge valve for the other end of the furnace opened as the gas reversing valve at the first end of the furnace is being opened and the 'gas reversing valve at the second end of the furnace .is being closed.

11. In reversing furnace mechanism, the

combination of gas reversing valves at opposite ends of the furnace, a purge valve at each end of the furnace, means whereby the purge valve at one end of the furnace will be closed and the purge valve at the other end of the furnace opened as the gas reversing valve at the first end of the furnace is being opened and the gas reversing valve at thesecond end of the furnace is being closed, and a gas shut-off valve at the second end of the furnace operatively connected to the purge valve at the second end of the furnace whereby said purge valve at the second end o-f the furnace is closed as said shut-off valve is opened.

12. In reversing furnace mechanism, the combination of a gas 'shut-off valve at each end of the furnace, a gas reversing valve at eachend of the furnace, a purge valve at each end of the furnace whereby the furnace may be purged of gas under cert-ain conditions, means whereby upon a closing of the gas shut-off valve at the first end of the furnace the purge valve at said end of the furnaceis opened and whereby upon the opening movement ofthe gas reversing valve at the first end of the furnace the purge valve kat said end will be closed and the purge valve at the second end of the furnace opened, and means whereby during an opening movement of thek gas shut-off valve at Vthe, second end of the furnace the purge valve will be closed.

13. In reversing furnace mechanism, the

combination of af gas shut-off valve ateach end of the furnace, a gas reversing valve at each end of the furnace, a purge valve at each end of the furnace whereby the furnace may be purged of gas under certain conditions, means whereby upon a c-losing of the gas shut-of`f valve at the first end of the furnace the purge valve at said end of the furnace is opened and whereby upon the opening movement of the gas reversing valve at the first end of the furnace the purge valve at said end' will bey closed and the purge valve at the second end of the furnace opened, means whereby during an opening movement of the gas shut-off valve at the second end of the furnace the purge valve at the second end will be closed, and wherebyv upon a closing movement of the gas shutoff valve at the second end of the furnace the purge valve at thesaid end will be opened and whereby an opening` movement of the reversing valve at the second end of the furnace will cause a closing movement -of the purge valve at the second end of the furnace and an opening movement of the purge valve at the first end of the furnace, and means whereby an opening movement of the gas shut-off valve at the first end of the furnace will cause a closing movement of the purge valve at' said end of the furnace.

, 14C. In reversing` furnace mechanism, the combination of gas supply means at opposite ends ofthe furnace, means whereby the furnace may be purged of gas from opposite ends thereof to prevent explosions in parts of the furnace, gas reversing valves at opposite ends of the furnace, means whereby gas may be purged from onel end of the furnace when the gas supply is shut off from said end of the furnace and whereby the purging action ceases when the gas reversing valves are reversed so that the gas reversing valve at the first end of the 'furnace is opened when the purging action` from that end of the furnaceA ceases, and means whereby the furnace is purged on the second end of the furnace when the gas supply from the second end of the furnace is shut off. y

15. In reversing furnace mechanism, the combination of gas supply means for opposite ends of the furnace, means whereby the furnace is purged of gas from opposite ends thereof to prevent explosions in parts of the furnace, gas reversing valves for opposite ends of the furnace, meansA whereby gas may be purged from one end of the furnace when the gas supply is shut off from said end of the furnace and whereby the purging action ceases when the gas reversing valves are reversed so that the gas reversing valve at the first end of the furnace is opened when the purging action from that end 0f the'furn'ace ceases, means whereby the furnace is purged on the sec- Cil ond end of the furnace when the gas supply from the second end of the furnace is shut off, and means whereby the purging` action from the second end of the furnace ceases after the gas reversing valve at the second end of the furnace is movedinto an open position. n

16. In reversing` furnace mechanism, the combination of a gas shut-off valve for each end of the furnace, a purge valve for each end of the furnace whereby under certain conditions the furnace may be purged of gas from opposite ends thereof, and means whereby under certain conditions both of said purge valves will remain closed to prevent the supply of any oxygen when both of the gas shut-off valves at opposite ends of the furnace are opened.

17. In reversing furnace mechanism, the combination of gas supply means at opposite ends of the furnace, means whereby the furnace may be purged from opposite ends of the furnace under certain conditions to prevent explosions in parts of the furnace, and means whereby under certain conditions no purging action will take place from either end of the furnace when gas is being supplied from both ends of said furnace.

18. In reversing furnace mechanism, the combination of a gas shut-off valve, a gas reversing valve, a purge valve whereby the furnace may be purged of gas, and ameans whereby the purge valve remains closed in the event that the gas reversing valve is opened before the gas shut-of valve is closed.

19. In reversing furnace mechanism, the combination of a gas shut-off valve, a gas reversing valve, a purge valve whereby the furnace may be purged of gas, and means whereby the purge valve remains closed if the gas reversing valve is given a certain movement prior to a certain movement of said gas shut-off valve.

20. In reversing furnace mechanism, the combination of means for supplying gas, a gas reversing valve, means whereby the furnace may be purged of gas to prevent eX- plosions in parts thereof, and means whereby no purging action can take place from said purging meanswhile gas is being supplied even though the gas reversing valve at the same end of the furnace is given a reversing movement. y.

21. In reversing furnace mechanism, the combination. of means for supplying gas, an air reversing valve, means whereby the furnace may be purged of gas to prevent explosions in parts thereof, and means whereby no purging action can take place from said purging means while gas is being supplied even though the air reversing valve at the same end of the furnace is given a reversing movement.

22. In reversing furnace mechanism, the combination of means for supplying gas, gas and air reversing valves, means whereby the furnacemay be purged of gas to prevent explosions in parts thereof, and means whereby no purging action can take place from said purging means while gas is being supplied even though the gas and air reversing valves at the same end of the furnace are given a reversing movement.

23. In reversing furnace mechanism, the combination of a gas shut-off valve, a reversing valve, a purge valve at the same end of the furnace, and means whereby under certain conditions said purge valve is jointly controlled by said gas shut-off valve and said reversing valve.

Signed at Buffalo, New York, this 9th day of July, 1920.

MARCUS C. STEESE. 

